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Table 3 P-box substitutions in E. coli NarQ.

From: The small FNR regulon of Neisseria gonorrhoeae: comparison with the larger Escherichia coli FNR regulon and interaction with the NarQ-NarP regulon

Plasmid Substitutions P-box sequence Phenotype
pBADEcQ E. coli NarQ P-box DAEAINIAGSLRMQSYRL Nitrate and nitrite sensing
pRNW18 R54K DAEAINIAGSLK MQSYRL Ligand insensitive
pRNW19 N48E I49E DAEAIEE AGSLRMQSYRL Ligand insensitive
pRNW20 N48E I49E R54K DAEAIEE AGSLK MQSYRL Ligand insensitive
pRNW29 D43A E45S A46V N48E I49E A ASV IEE AGSLRMQSYRL Ligand insensitive
pRNW30 D43A E45S A46V A ASV INIAGSLRMQSYRL Ligand insensitive
pRNW31 D43A E45S A46V R54K A ASV INIAGSLK MQSYRL Ligand insensitive
pRNW32 D43A E45S A46V N48E I49E R54K A ASV IEE AGSLK MQSYRL Ligand insensitive
pRNW33 D43A E45S A46V S52N S57A A ASV INIAGN LRMQA YRL Ligand insensitive
pRNW34 D43A E45S A46V N48E I49E S52N R54K S57A A ASV IEE AGN LK MQA YRL Ligand insensitive
  1. E. coli strains JCB391 (narXL narQ) or JCB12 (narXL narQ frdA::lacZ) transformed with pBADecQ expressing wild-type or mutated NarQ proteins were grown anaerobically in LB in the absence or presence of 20 mM NaNO3 and the β-galactosidase activities determined. Mutations in the P box are shown in bold type. Wild-type NarQ was able to phosphorylate NarP in the presence of nitrate, activating expression of nirB and repressing frdA. Mutated NarQ proteins were inactive.